The objective of this project is elucidation of the sequence of molecular events involved in expression of one set of functionally related eucaryotic genes and control of that expression. These studies are to serve as a basis for addressing the mechanisms operating in the development and onset of malignancy in human cells. We have recently shown in Saccharomyces cerevisiae that: (1) allantoin is degraded in 5 steps to NH3 and CO2, (2) allophanic acid is the inducer for the synthesis of at least three of the allantoin degradative enzymes, (3) the genes for these five enzymes appear to be organized in two unlinked clusters, (4) the last two enzymes of the pathway are a multienzyme complex, and (5) the capacity for continued synthesis of the last pathway enzyme decays with a half life of 3 minutes following removal of inducer. To provide information concerning the events giving rise to these observations we plan to pursue the following areas. (1) Large scale purification and physico-chemical characterization of the urea carboxylase:allophanate hydrolase multienzyme complex and production of antibody preparations against the complex and its isolated subunits; (2) establishment of the biochemical relationships between allantoinase, allantoicase and ureidoglycolate hydrolase; (3) assembly and interaction of urea carboxylase and allophanate hydrolase into a functional multienzyme complex; (4) translation of allantoin degradative system mRNA by a wheat embryo system; (5) coordinancy relationships of the allantoin degradative enzymes; (6) induction and repression occurring in temperature sensitive, non-nutritional mutants; (7) isolation and characterization of mutants that are resistant to nitrogen repression and (8) completion of genetic and physiological characterization of the allantoin degradative system.